The proposed research involves an ongoing effort to understand the molecular basis of portein structure and function. Specific objectives include: a) Studying the magnitude and effects of electrostatic interactions in a number of proteins. Charged amino acids located near the retinal chromophore of visual pigments have been shown to be responsible for their color. We wish to determine whether the electric fields produced by these residues are also responsible for the surprisingly efficient photochemical processes and energy storage mechanisms of these pigments. Other systems of interest include bacteriorhodopsin, chlorophylls, and glycogen phosphorylase. b) Characterizing helix-helix packing patterns in different proteins. Of particular interest will be proteins which contain long stretches of parallel a-helical bundles such as TMV coat protein, When more experimental data is available, we will use our results to construct a detailed molecular model of bacteriorhodopsin.